Comparison of vascular perfusion in ischemia-sensitive and ischemia-resistant regions of gerbil brain by an automated laser cytometric device: a preliminary study.

Reduced blood supply in the hippocampus has been considered to be a factor contributory to this region's selective susceptibility to ischemia. To determine if there are differences in vascularization of vulnerable and resistant regions of the brain, a quantitative morphometric assessment of vascular filling was performed in the gerbil brain by using a relatively new and highly sensitive automated laser cytometric device, ACAS (Adherent Cell Analysis and Sorting). Evan's blue, an intravital vascular tracer, was injected intracardiac in 5 Mongolian gerbils to identify perfused blood vessels in the cortex and CA1 region of hippocampus. Exactly 3 min later, the animal was decapitated, the brain removed and sections prepared for fluorescent quantitative morphometric analysis of blood vessels. The perfused vessels appeared as fluorescent structures due to the autofluorescent property of Evan's blue. Several fields in each of the two specified regions were studied and integrated numbers of blood vessels/mm2 obtained for statistical comparisons. Control brains perfused with normal saline (vehicle for Evan's blue) were used to determine the background fluorescence. The number of perfused blood vessels of all sizes was found to be lower in the CA1 sector of hippocampus than that in the cerebral cortex. The number of capillary size vessels was also lower in the CA1 region but the difference was not significant. Since it is the capillaries that are of prime importance in the diffusion system, and we found no significant regional difference in the density of capillary size vessels, it appears unlikely that the peculiarities of patterns of vascularization contribute significantly to vulnerability to ischemia.